It is b because it just is
A dissection microscope<span> is light illuminated. The image that appears is three </span>dimensional<span>. It is used for dissection to get a better look at the larger specimen. You cannot see individual cells because it has a low magnification. Or just call it a dissecting microscope</span>
Three important characteristics such as a notochord, a dorsal hollow nerve cord, and pharyngeal gill slits, should appear at any stage of their life cycle. These are the characteristics of the chordates. Members of echinoderms share resemblance with chordates in presence of a notochord.